/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.utils.resolver.implementations;

import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;
import com.sun.org.apache.xml.internal.security.utils.XMLUtils;
import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverContext;
import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverException;
import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolverSpi;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * Handles barename XPointer Reference URIs.
 * <BR />
 * To retain comments while selecting an element by an identifier ID,
 * use the following full XPointer: URI='#xpointer(id('ID'))'.
 * <BR />
 * To retain comments while selecting the entire document,
 * use the following full XPointer: URI='#xpointer(/)'.
 * This XPointer contains a simple XPath expression that includes
 * the root node, which the second to last step above replaces with all
 * nodes of the parse tree (all descendants, plus all attributes,
 * plus all namespaces nodes).
 *
 * @author $Author: coheigea $
 */
public class ResolverXPointer extends ResourceResolverSpi {

  /**
   * {@link org.apache.commons.logging} logging facility
   */
  private static java.util.logging.Logger log =
      java.util.logging.Logger.getLogger(ResolverXPointer.class.getName());

  private static final String XP = "#xpointer(id(";
  private static final int XP_LENGTH = XP.length();

  @Override
  public boolean engineIsThreadSafe() {
    return true;
  }

  /**
   * @inheritDoc
   */
  @Override
  public XMLSignatureInput engineResolveURI(ResourceResolverContext context)
      throws ResourceResolverException {

    Node resultNode = null;
    Document doc = context.attr.getOwnerElement().getOwnerDocument();

    if (isXPointerSlash(context.uriToResolve)) {
      resultNode = doc;
    } else if (isXPointerId(context.uriToResolve)) {
      String id = getXPointerId(context.uriToResolve);
      resultNode = doc.getElementById(id);

      if (context.secureValidation) {
        Element start = context.attr.getOwnerDocument().getDocumentElement();
        if (!XMLUtils.protectAgainstWrappingAttack(start, id)) {
          Object exArgs[] = {id};
          throw new ResourceResolverException(
              "signature.Verification.MultipleIDs", exArgs, context.attr, context.baseUri
          );
        }
      }

      if (resultNode == null) {
        Object exArgs[] = {id};

        throw new ResourceResolverException(
            "signature.Verification.MissingID", exArgs, context.attr, context.baseUri
        );
      }
    }

    XMLSignatureInput result = new XMLSignatureInput(resultNode);

    result.setMIMEType("text/xml");
    if (context.baseUri != null && context.baseUri.length() > 0) {
      result.setSourceURI(context.baseUri.concat(context.uriToResolve));
    } else {
      result.setSourceURI(context.uriToResolve);
    }

    return result;
  }

  /**
   * @inheritDoc
   */
  public boolean engineCanResolveURI(ResourceResolverContext context) {
    if (context.uriToResolve == null) {
      return false;
    }
    if (isXPointerSlash(context.uriToResolve) || isXPointerId(context.uriToResolve)) {
      return true;
    }

    return false;
  }

  /**
   * Method isXPointerSlash
   *
   * @return true if begins with xpointer
   */
  private static boolean isXPointerSlash(String uri) {
    if (uri.equals("#xpointer(/)")) {
      return true;
    }

    return false;
  }

  /**
   * Method isXPointerId
   *
   * @return whether it has an xpointer id
   */
  private static boolean isXPointerId(String uri) {
    if (uri.startsWith(XP) && uri.endsWith("))")) {
      String idPlusDelim = uri.substring(XP_LENGTH, uri.length() - 2);

      int idLen = idPlusDelim.length() - 1;
      if (((idPlusDelim.charAt(0) == '"') && (idPlusDelim.charAt(idLen) == '"'))
          || ((idPlusDelim.charAt(0) == '\'') && (idPlusDelim.charAt(idLen) == '\''))) {
        if (log.isLoggable(java.util.logging.Level.FINE)) {
          log.log(java.util.logging.Level.FINE, "Id = " + idPlusDelim.substring(1, idLen));
        }
        return true;
      }
    }

    return false;
  }

  /**
   * Method getXPointerId
   *
   * @return xpointerId to search.
   */
  private static String getXPointerId(String uri) {
    if (uri.startsWith(XP) && uri.endsWith("))")) {
      String idPlusDelim = uri.substring(XP_LENGTH, uri.length() - 2);

      int idLen = idPlusDelim.length() - 1;
      if (((idPlusDelim.charAt(0) == '"') && (idPlusDelim.charAt(idLen) == '"'))
          || ((idPlusDelim.charAt(0) == '\'') && (idPlusDelim.charAt(idLen) == '\''))) {
        return idPlusDelim.substring(1, idLen);
      }
    }

    return null;
  }
}
